1. Field of the Invention
The invention relates generally to compressing graphical data for three-dimensional objects. More particularly, the invention relates to a system and method for efficiently compressing graphical data that describes the appearance of a three-dimensional object from multiple viewing directions.
2. Background Information
Accurate portrayal of the physical world has been an important goal of computer graphics since its inception. This includes modeling the geometry and surface attributes of the object when the object is illuminated by a light source and viewed in a virtual environment from a certain vantage point. Typically, the geometry is modeled as a polygonal mesh that models the geometric extents of the object. The surface attributes, which can be modeled in a number of ways, are then applied to the geometry during rendering to graphically display the object.
The essential part of the quest for realistic graphics is proper modeling of the visual attributes of the surfaces of objects. For example, proper modeling of surfaces that have luster, reflections, such as chrome reflections, semi-transparent regions, complex textures like fur, and other qualities, is needed to create realistic visual models of many real-world objects. Theoretical and empirical approaches are possible.
Historically, parametric reflectance models, such as Phong shading, have been favored since they are simple and compact. However these techniques can be inaccurate, are difficult to implement on traditional graphics hardware, and are challenging to develop. An alternative is to use image-based techniques. Such image-based techniques offer a simple method of acquiring the visual data and an accurate method for portraying the physical world. They represent discrete visual data, acquired from the physical world using a variety of imaging devices, directly in the sample-based format without resorting to the parametric models.
However the amount of data associated with such models is enormous. This significantly limits their use, since storage, data transmission, and rendering suffer as a result of the large size of these models. Many images are needed to display the object from different vantage points without creating artifacts. Some approaches interpolate between two related images to reduce the amount of data required, however this approach does not significantly reduce the amount of data needed, and many images are still required to display visually-realistic objects.